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Anger Camera for neutrons

Anger Camera for neutrons

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Anger Camera for neutrons

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  1. Anger Camera for neutrons F. A. F. Fraga, L. M. S. Margato ,S. T. G. Fetal, M. M. F. R. Fraga, A. Morozov, L. Pereira, R. Ferreira Marques, P. Mendes, J. P. Rodrigues LIP Coimbra, Universidade de Coimbra

  2. FP6 NMI3 JRA2 RII3-CT-2003-505925 ended 2008 • MILAND – development of thermal neutron detectors • Would increase knowledge about neutron detectors, but should have a deliverable • working detector prototype with a firm and clear specification • 32 x 32 cm2 detector • 1 mm resolution (FWHM) res/length = 3x10-4 • 1 MHz global count rate • 100 kHz / mm2 local (peak) count rate • Gamma background rejection 10-8 • 50% efficient at 1.8Å • parallax free • Cost is critical • Partners and Observers • P1 CCLRC N. Rhodes (UK) T3, T6, T7 • P2 GKSS R. Kampmann (Germany) T1, T4, T5, T6, T7 • P3 BNC L. Rosta (Hungary) T1, T5, T6, T7 • P4 ILL B. Guerard (France) T1, T2, T3, T4, T5, T6, T7 coordinator • P5 LLB C. Fermon (France) T2, T4, T6, T7 • P6 FRM-II K. Zeitelhack (Germany) T1, T2, T4, T6, T7 • P7 LIP F. Fraga (Portugal) T2, T3, T6, T7ObserversEFO1 BNL G. Smith (USA) • EFO2 SNSR. Cooper (USA) • EFO3 TU H. Takahashi (Japan) • EFO4 RAL J. Mir (UK) • EFO5 BNL R. Krueger TU Delft (NL) Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy

  3. Neutron Detectors nuclear reactions to convert neutrons • n + 3He  3H + 1H + 0.764 MeVGaseous detectors (CF4, prop.) • n + 6Li  4He + 3H + 4.79 MeVScintillators • n + 10B  7Li* + 4He7Li + 4He + 0.48 MeV +2.3 MeV (93%) 7Li + 4He +2.8 MeV ( 7%) • n + 155Gd Gd* -ray spectrum  conversion electron spectrum • n + 157Gd Gd* -ray spectrum  conversion electron spectrum • n + 235U  fission fragments + ~160 MeV • n + 239Pu  fission fragments + ~160 MeV

  4. Scintillators for Neutron Detectors CWE van Eijk, NIM A529(2004)260-267

  5. CF4+*, CF3+* CF3* Gaseous detectorsn + 3He  3H + 1H + 0.764 MeVCF4 should be added to control the range -3 bar for 1mm FWHM • CF4 is a good scintillator, but only a few primary photons • Secondary scintillation ~.3 photon per secondary electron

  6. Scintillation Anger camera PMT base PMT base PMT PMT Transparent window gas MSGC Neutron window

  7. New MSGC Batch • Remarks • Cathodes width of the new set of microstrips is more or less half of the older ones (181 mm vs.398mm) and the anodes seems to be larger. • To achieve the same charge gain the new microstrip needed a higher anode voltage than the older one. • For instance, at 1 bar of CF4, to reach a gain of G ~103 we should apply a voltage of Va~1900V, something like 840V more than in the older microstrip (Va=1060V). • Taking off the drawbacks linked to a higher voltage, the light yield obtained with the new microstrip (for G ~103 ) is ~ 0.263 ph/sec-e, about 4.5 times higher than the light yield in the older one (~0.045 ph/sec-e). • This MSGCs batch are unable to operate above 1 bar CF4 (discharges). NMI3 Meeting, CORSICA, 25-28th June 2008

  8. Charge gain and light/charge versus anode voltage 15, 20 and 30µm anodes CF4 (1bar)

  9. New MSGC Batch • Charge and light measurements Number of emitted photons per secondary electron Charge gain versus anode voltage NMI3 Meeting, CORSICA, 25-28th June 2008

  10. MSGC ILL6C at High pressure • Measurements at 3 bar CF4 Number of emitted photons per secondary electron Charge gain versus anode voltage NMI3 Meeting, CORSICA, 25-28th June 2008

  11. Simulations F.Fraga, Hamburg meeting

  12. GSPC details

  13. Aquisition system by Acquiris and E. Shooneveld GSPC in position at the ILL beam

  14. 2D position images Vanode = 1360, 1550 1650 and 1850V

  15. Mask_1650_3.eve: Va=1650 V; VPMT= 800 V.

  16. Mask_1650_3.eve: Va=1650 V; VPMT= 800 V FHWM center peak 1.63 mm FHWM center peak 1.68 mm

  17. FWHM resolution versus Vanode • For the best safe conditions (Vanode =1850 V; VPMT= 800 V) the intrinsic resolution is 1.1mm after we deconvolute the beam width

  18. Detector uniformity (1850V)

  19. Typical PMT signals High amplitude – good discrimination Very fast signals – risetime ~20ns

  20. Transparent electrode MSGC • Manufactured at the Tokyo University and supplied by Hiroyuki Takahashi • 90% ITO electrode transparency • The transparent window can be the active element • Multigrid approach proposed –it has the advantage of a very high local count rate.

  21. ITO M - MSGC • Photographs NMI3 Meeting, CORSICA, 25-28th June 2008

  22. ITO M - MSGC • Experimental Setup • Driftlength = 10 mm • Distance between microstrip and PMT = 34.8mm NMI3 Meeting, CORSICA, 25-28th June 2008

  23. ITO M - MSGC • Ar+5%CF4 (1atm, 100cc/min.) and CF4 (1atm, 100cc/min.) Number of emitted photons per secondary electron Charge gain versus anode voltage NMI3 Meeting, CORSICA, 25-28th June 2008

  24. ITO M - MSGC • Effect of GRID potential (Vg) on Gain and light yield Charge gain versus anode voltage for several GRID voltages Number of emitted photons per secondary electron NMI3 Meeting, CORSICA, 25-28th June 2008

  25. 60ns 100 mV ITO M - MSGC • Example of typical signal taken directly from the PMT Hamamatsu R1387 (RL=50 W): 55Fe (5.9keV) X-ray source • 100%CF4 (1atm) • Vdrift= -500V, Vcathode=0 • Vanode=990V Vg1= 600V • VPMT=-1000V NMI3 Meeting, CORSICA, 25-28th June 2008

  26. MSGC ILL6C at High pressure • Measurements at 3, 4 and 5 bar CF4 Number of emitted photons per secondary electron Charge gain versus anode voltage NMI3 Meeting, CORSICA, 25-28th June 2008

  27. 2009-2011 FP7 WP22CP-CSA_INFRA-2008-1.1.1 Number 226507-NMI3 Development of new thermal neutron detector technologies based on Gaseous Scintillation Proportional Counters (GSPC) • Explore their potential to overcome the limitations in light output and rate capability of existing scintillation detectors • Investigate their potential as high resolution detectors for Reflectometry or time resolved SANS. • Built and study small scalable prototypes http://detectors.neutron-eu.net/Detectors

  28. The new family members, born in Munich two months ago! We will go on studying the scintillation and the PMT readout

  29. The good not so good new • European Spallation Source (ESS) went to Lund in Sweden The bad new • 3He crisis